In cooperation with the commanding officer's brother Ernst Steinhoff of the Peenemünde Army Research Center, a rack of six rockets were mounted on deck, and were successfully launched while on the surface and while submerged up to a depth of 12 metres (39 ft).

However, the rockets were not particularly accurate and the racks on the deck had a negative effect on the U-boat's underwater handling and performance, so the project was abandoned.

The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged.

At 06:29 on 27 August, U-511 fired a spread of four torpedoes at Convoy TAW-15, en route from Trinidad to Key West, about 120 nautical miles (220 km; 140 mi) south-south-east of Guantánamo Bay in Cuba, sinking two ships and damaging another.

[7] The 8,968 GRT Dutch tanker Rotterdam, carrying 11,364 tons of gasoline was struck and immediately began to settle by the stern.

[8] The 8,773 GRT American tanker Esso Aruba, loaded with 104,170 barrels (16,562 m3) of diesel fuel and serving as the flagship of the convoy commodore, was hit by a single torpedo on the port side which badly damaged the ship, but left the engines and steering gear still operating.

[2] U-511 sailed from Lorient on 24 October 1942, and patrolled the waters off the coast of north-west Africa before returning to base after 36 days, on 28 November, having had no successes.

[10] U-511, now under the command of Oberleutnant zur See Fritz Schneewind, left Lorient once more on 31 December 1942 to patrol the waters between Spain, the Canary Islands and the Azores.

Leaving Lorient on 10 May 1943 under the command of the now Kapitänleutnant Fritz Schneewind, she sailed through the Atlantic and around the Cape of Good Hope into the Indian Ocean where she made two kills.

[13][14] The first attack was made at 09:42 on 27 June, when she hit the unescorted 7,194 GRT American Liberty ship Sebastian Cermeno with two torpedoes, disabling the engines and killing an officer and two men.

[15] Her second success came on 9 July when she torpedoed the 7,176 GRT American Liberty ship Samuel Heintzelman, loaded with 5,644 tons of ammunition and general cargo.

After Japan's surrender, the crew of Ro-500, led by Lieutenant Yasuhisa Yamamoto, joined the rebels that wanted to continue the war against the Soviets.

[1][14] In 2018, an expedition led by the Society La Plongee for Deep Sea Technology discovered the wrecks of Ro-500 and I-121 in Wakasa Bay off the coast of Kyoto Prefecture.